Recently, portable, battery-driven notebook and netbook personal computers have been gaining much popularity. Various features for saving power are incorporated in computers of this type in order to maximize the battery operating time.
For example, Jpn. Pat. Applin. KOKAI Publication No. 2006-40293 discloses optimization of a link speed of a serial advanced technology attachment (hereinafter abbreviated as SATA) interface. More specifically, a mechanism for restraining wasteful power consumption by controlling use of a needlessly high link speed which is incompatible with system specifications.
In general, in a computer which performs data transfer to/from hard disk drives (HDDs) and optical disk drives (ODDs) by a SATA interface, the operating system thereof is restarted (to give an opportunity for an initial setting for a SATA host controller) to switch the link speeds of the SATA interface.
Therefore, for example, if a request for reducing power consumption is issued upon pulling-out an alternating current (AC) adapter during power-on of such a computer, the request for reducing power consumption cannot instantly be responded to by reducing the link speed of the SATA interface thereof (without restarting the operating system). In other words, reduction of a link speed of a SATA interface cannot be achieved when a normal mode is dynamically switched to a power saving mode.